This is a priority application based upon German patent application 199 46 787.0, filed Sep. 29, 1999.
The invention relates to a method and a device for diagnosing machines for manufacturing products such as cigarettes and/or cigarette packets, in particular cigarette-packaging machines. In the case of such a method, the products are examined for faults and a signal indicating a faulty product is generated. Such a device correspondingly has fault-detecting means for investigating whether a product is faulty, and for generating a signal indicating a, faulty product.
Machines of the above type are generally of very complex design. A multiplicity of various subassemblies and tools cooperate in order to manufacture cigarettes and/or finished cigarette packets or other products, including packaging them. Disturbances which impair the product to be manufactured can arise in the case of each individual subassembly or tool. In order to ensure unchanged product quality, the products are examined at the end or during the course of processing with regard to possible faults. If a fault is detected, this is indicated by a corresponding signal, and the product is removed from the course of processing.
It is customary to use a range of sensors on different subassemblies or tools in order to locate the faulty subassemblies or tools causing the faulty products. However, it is not possible in practice to monitor every subassembly or every tool. Consequently, the diagnosis of machines after the occurrence of a fault is frequently very difficult and it is necessary to. dismantle and examine a multiplicity of subassemblies and tools. This leads to high costs and is therefore disadvantageous.
The invention is therefore based on the problem of improving the diagnosis of machines.
For the purpose of solving this problem, the method according to the invention is characterized in that the fault-indicating signal is evaluated for possible periodicity, in particular one or more periods, of faulty products, and a possible periodicity is determined. A device according to the invention is characterized by a control device which is constructed in such a way that it is possible to determine and specify a periodicity of the fault-indicating signal.
The terms below are used as follows in conjunction with the invention and preferred embodiments of the invention. The term xe2x80x9cproductsxe2x80x9d is understood as all end, intermediate and initial products during a manufacturing process, including a packaging process, in particular finished and unfinished cigarette packets or cigarettes in the region of the cigarette manufacturing and/or packaging.The term xe2x80x9cperiodicityxe2x80x9d is to be understood as any periodic characteristic of the fault-indicating signal. The fault-indicating signal can, in particular, exhibit one or more periods. The term xe2x80x9ccyclexe2x80x9d is to be understood as any regular movement, in particular movement with a temporary standstill, but also continuous movements. The term xe2x80x9csubassemblyxe2x80x9d is understood as any unit of tools, in particular so-called turrets such as folding, transfer or drying turrets, pocket chains or else magazines and shaft groups. The term xe2x80x9ctoolsxe2x80x9d is to be understood as individual elements of a subassembly, for example individual pockets of a pocket chain or of a turret, and shafts of shaft groups.
The invention is based on the finding that in machines of the above-named type many subassemblies operate cyclically and, for this purpose, have a specific number of tools. If an individual tool of a subassembly operates defectively, individual manufactured products are faulty, at least with an increased probability, specifically with a period which corresponds to the number of tools of this subassembly. Since the individual subassemblies of a machine generally have a characteristic number of tools, the faulty products occur with a period corresponding to this number. Consequently, a faulty subassembly or a subassembly having the faulty tool can be detected with the aid of its characteristic period.
Faulty products can, however, also occur with several different periods. This is the case. when a machine fault impairs several subassemblies with different periods, something which can, in particular, be associated with a fault in a transition region of two subassemblies.
If, for example, a subassembly 24 has tools of which one is faulty, and in which case the subassembly advances by one tool with each machine cycle, the result is a fault period of 24 machine cycles in the examined products. In the case of other subassemblies, however, a plurality of tools can be advanced per machine cycle. It is likewise possible for a tool to be advanced one position only after several machine cycles. In each case, however, the result in the case of such cyclically operating subassemblies is one or more characteristic periods, and it is therefore possible to conclude that there are one or more faulty subassemblies given the occurrence of a corresponding periodicity in the fault-indicating signal. Furthermore, it is also possible to locate the respective tool when the spacing, in particular in machine cycles, between the fault-detecting means and a reference position, for example the uppermost tool, is known.
If it is not possible upon the occurrence of faulty products to determine a specific periodicity, and/or the fault occurs with the same probability for each product or machine cycle, the invention assumes that all tools. are uniformly affected by a fault.